After the removal of trading, why is it still possible to get duplicate Black Market items? What am I supposed to do with them?

I find it really unfair that after the removal of trading, it's still possible to get duplicate Black Market items from drops. At least with lower rarity items, you can do trade-ups, but with these, you can't.

I have 3 copies of 20XX, and I have no idea what to do with them. What's the point of getting the same items over and over without the ability to trade or do anything useful with them?